Hydrocarbon conversion process and apparatus



Feb. 16, 1960 J MlTCHELL 2,925,378

HYDROCARBON CONVERSION PROCESS AND APPARATUS Filed April 29, 1958 CATALYST PRODUCT OUT.

REACTANT gm i 3 REACTANT INVENTQR Jehn Gflflltchall CATALYST ATTORNEY is screened from the charge stream by the contactmaterial particles in these regions. The vapor or gaseous material formed by converting the liquid or vaporizing it, as well as any hydrocarbon charge 'suppliedtas vapor, disengages from mass 16 and'passes into gas space 15. This technique for supplying liquid: or mixed phase hydrocarboncharge is thesubject of claims in United States patent application Serial Number 719,645; filed March 6, 1958. a

Extending across housing at a level substantially below partition 11 but substantially above the lower end of the housing is a second horizontal partition 21 which defines afirst conversion chamber between partitions 11 and 21. A plurality of contact material conduits 22 extend through partition 11 to communicate on their inlet ends with the lower section of accumulation 16. These conduits extend downwardly to terminate a spaced distance below partition 11 butfa substantial distance above partition 21 on spaced outlets. Contactmaterial flows through conduits 22 to fill up the space betweenmthe lower ends of conduits 22 and partition21 and formthereiir a first compact reaction bed 23. Defined above .bed 23,

between the lower ends of conduits 22'andfpartitioh'11,

is a gaseous product collecting space 24, from which gaseous product outlet 25 with control valve 261extends.

Also extending from the lower section of accumulation 16 through partition 11 and then through partition 21 and terminating a spaced distance therebelow are conduits 27. These conduits act to form a second compact reaction bed of contact material 28 and above bed 28 a vapor distributor plenum space 29. Spent contact material from the lower end of reaction bed 23 passes downwardly through conduit 30. It is discharged adjacent the lower end of bed 28 to blend with spent contact material from bed 28. Immediately below the lower ends of conduits 30 there is provided a conventional gas disengaging system employing inverted troughs 36 which remove vapor products from the contact material and feed them by means of passages, not shown, to conduit 31, by which they are removed from vessel 10'. All of the spent contact material exlts from vessel 10 through conduits 32 and may be passed to a conventional regenerator system for reconditioning for re-use in the reaction stages. I V Y I In operation, then, vaporized charge from gas space is passed through conduit 33 into distributor plenum space 29. Any additional vapor charge desired may be added to the plenum space by means of conduit 34. Apart of this vapor passes upwardly into the lower end of reaction bed 23 through distributors 35. These distributors may be of any conventional design. For example, they might be short nipples with caps spaced thereabove to keep catalyst from falling through the nipples. This vapor spreads itself across reaction bed 23 and flows upwardly therethrough to undergo the desired conversion. Gaseous products collect in space 24 to be removed through conduit 25 at a rate controlled by valve 26. V c

The remainder of the vaporized charge flows downwardly through reaction bed 28 to undergo the desired conversion there. The gaseous products formed would be removed from the bed, as indicated above, by conventional gas collecting devices 36 and removed fromvessel 10. by means of conduit 31.

Conduit 37 may be used to refill reactor 10 lyst after shutdowns.

- In-the application of this invention, illustrated in the drawing, conduits 30, for the removal of used contact. material from first reaction bed 23, discharge that contact material into the lower section of second reaction bed28' to mix with the used contact material there so. that the stream of used contact material leaving the vessel through conduit 32 will be a mixture of contact material from both: conversion 'zones. This is particularly advantageous where a single unit is used to re'condition contact material for re-usein'the conversion zones because by. this technique a stream representative of both reaction zoneswill be fed to the reconditioning'unit. This unit, therefore,

.With icatawill not have to operate for a time on contact material from one reaction zone and at other times on contact material from the other reaction zone, perhaps requiring different conditions for reconditioning.

It is a feature of this invention that the blending of contact material from the two reaction zones may be accomplished without the use 10f proportioning valves or like devices tocontrol the rates of flow through. the two zones.

I In the drawing the lower ends of conduits 30 are enlarged so that the total horizontal area which they cover is in ratio to the'horizontal area between the lower ends of conduits 30 the same as the ratio of the desired contact material fiow rate; through reaction bed 23 to the desired contact material fiow rate through reaction bed 28. The

fiow ratio through the two beds will then always be in the 7 carbon charge which passes through the upper: reaction zone isrcontacted by contact material in substantially the same condition as the contact material in the lower re action zone. Thus, the portion of the charge which flows through the lower bed can be contacted in the identical manner as the charge flowing through the upper bedto produce substantially identical products from each re action zone. Of course, if desired, conditions may be adjusted to produce different products from the two zones.

It isto be noted that; conduits 22automatically act as seal legs to prevent products from space 24 flowing back up into space 15. Since the pressure in space 15 must always be higher than the pressure in space 24, the flow of vapor will always be from 15 to 24. This may result in some material which is not fully converted passing out with the product through conduit 25. The quantity of this materialwill not normally be sufficient to materially affect this product and may be minimized by providing conduits 22 of suitable length and size to minimize flow therethrough, in accordance with conventional seal leg design principles. In any case, any charge material that is mixed with the productremoved through conduit 25 can readily be separated in the distillation equipment customarily; employed to fractionate-the product and such charge material maybe recycled to the reactor;

Where the gaseous material-flows through conduits22 at high velocities it may be desirableto-enlarge the lower 7 ends of-the conduits sufliciently that the gaseous material will be reduced in velocity prior to discharge from the conduits, thereby avoiding disruption of the. contact material;in the bed adjacent the lowerends of the, conduits.

The relative rates of flow between .upperand lower reaction zones may be adjusted by adjusting valve 26. As the valve is closed' a reduced portion of the charge will flow through the upper zone.

While a specific type of hydrocarbon feed system is shown in the drawing to be'associated with accumulation 16, other systems such as the conventional falling curtain systemmay be used within the broad scope of this invention. The system shown is, presently believed,.however, to-be the most advantageous. v The conduits. 27 which feed reaction bed'28 are advantageouslyspaced apart a center to center distance less than "20 inchesyto avoid lateral temperature diiferentials being set up across bed The contactmaterial used in this inventionfshould generally be oifa size within the. range one inch to mesh Tyler and preferably 4 to 20 'mesh Tyler. The 'term granular is .used herein .to refer to. contact material of this size whether'of regulator-irregular shape.

. Suitablecontact materials for use when this invention is applied to catalytic processes includenatural and treated steam clays, bauxite, activated alumina and'synthetic associations'of silica, alumina or magnesia or combinations In a unit for the catalytic cracking of 35,000 barrels per day of a petroleum-derived hydrocarbon r charge designed to-resemble the unit shown in the drawing, the charge might be supplied at 800 F. and a silica-alumina catalyst at 1085? F. The catalyst might be circulated at 630 tons per hour. Reaction vessel might be 16 feet in diameter and reaction bed 23 might be 5 feet deep. Conduits 30 might extend to a level 12 feet below the surface'of the bed 28v and their lower ends mighfioccupy 28.5 percent of the horizontal cross-sectional area of vessel 10. The products from both reaction beds would be substantially the same. It is estimated that by this design the seal leg feeding the reactor would be 2 5 feet less than the seal leg needed to achieve the same throughput with a conventional concurrent flow reactor.

This invention should be understood to include all changes and modifications of the examples of the invention herein, chosen for purposes of disclosure, which do not constitute departures from the spirit and scope of the invention.

I claim;

l. A process for the conversion of high boiling fluid hydrocarbons into lower boiling gaseous products in the presence of a moving mass of granular contact material, which comprises: maintaining an accumulation of granular contact material within the upper section of an enclosed housing; continuously supplying contact material to said accumulation; supplying hydrocarbon charge, at least partially in the liquid phase, to said accumulation; removing from said accumulation vapor formedfrom said liquid and any gaseous material'supplied with said liquid; maintaining a first compact reaction bed of contact material within said housing below said accumulation; maintaining a second compact reaction bed of contact material a spaced distance below said first reaction bed and within said housing so that a plenum space is defined between said beds; passing contact material as at least one confined stream from the lower section of said accumulation onto the upper surface of said first reaction bed; passing contact material from the lower section of said accumulation onto the upper surface of said second reaction bed; passing the gaseous material disengaged from said accumulation into said plenum space; passing gaseous hydrocarbon material from said plenum space into the lower end of said first reaction bed and upwardly therethrough to undergo the desired con- I version; passing gaseous hydrocarbon material from said plenum space onto the upper surface of said second reaction bed and downwardly therethrough to undergo the desired conversion; removing products of conversion from the upper section of said first reaction bed and from the lower section of said second reaction bed; removing used contact material from the lower section of said first reaction bed and removing used contact material from the lower section of said second reaction bed.

2. The process of claim 1 further limited to the conversion being the catalytic cracking of high boiling hydrocarbons to lower boiling hydrocarbons and the granular contact material being a granular catalyst.

3. The process of claim 1 where, in addition to the gaseous hydrocarbon material flowing from the gas space to the plenum space, there is also added to the plenum space a separate stream of vapor hydrocarbon charge.

4. The process of claim 2 wherein the used catalyst from the first reaction bed and the used catalyst from the second; reaction bed, aremixed within the housing and removed from the housing as at least one mixed stream.

5. Thesprocess of 'claim ,1 wherein the total hydrocarbon feed is injected-into said accumulation as a mixture of liquid and vapor at a suflicient velocity to disrupt said accumulation in the region of each injection point.

6. A process for the continuous conversion of high boiling hydrocarbons to lower boiling products in, the presence of a downwardlymoving'mass of granular contactmaterial, which comprises: maintaining a mass of granular contact material within the upper section of an enclosed housing; continuously supplying fresh contact material to the upper surface of said accumulation; maintainingat least 'a portion of the upper surface of said accumulation unconfined and in open communication with a gas space thereabovewithin said housing; injecting hydrocarboncharge as a mixture of liquid and vapor into said accumulation and disengaging vapor as a part of said charge and vapor formed from the liquid part of said charge from said accumulation through said unconfined surface into said gas space; maintaining a first reaction bed of granular contact material within saidhousing with upper surface a spaced distance below said accumulation so as to form a vapor collection space; maintaining a second reaction bed within said housing with its upper end a spaced distance below the lower end of said first bed so that a vapor plenum space is defined between said beds within said housing; continuously passing contact material from the lower end of said accumulation ontov the upper surface of said first reaction bed as a plurality of spaced confined streams; continuously passing contact material from the lower section of said accumulation onto the upper surface of said second reaction bed as a plurality of spaced confined streams; continuously removing contact material from the lower end t of said first bed as a plurality of confined streams and discharging said confined streams at a plurality of uniformly spaced points into said second bed adjacent the lower end thereof to mix with contact material in said second bed; continuously passing vapor from said gas space into said plenum space; injecting vapor from said plenum space into the lower end of said first reaction bed at a plurality of uniformly spaced points and passing said vapor upwardly through said first reaction bed into said vapor collection space; continuously passing vapor reactant from said plenum space into the upper end of said second bed and downwardly therethrough to convert the reactant to desired products and removing said products from said second reaction bed at a level below the level where contact material from said first and second beds is mixed; continuously removing contact material from the lower section of said second bed and said housing below the level of product removal.

7. An apparatus for the conversion of fluid reactants to other desired products, which comprises in combination: an enclosed reaction vessel; a first partition extending horizontally across the upper section of said vessel; means for supplying granular contact material to said vessel at a level above said first partition, so that an accumulation of contact material will form therein above said partition; a second partition extending horizontally across said vessel a substantial distance below said first partition, thereby defining a first conversion chamber thereabove and a second conversion chamber therebelow; a first plurality of conduits extending tightly through said first partition so as to communicate with said accumulation of contact material at their inlet ends and terminating on horizontally spaced outlets within the upper section of said first conversion chamber a spaced distance below said first partition but substantially above said second partition, whereby a contact material bed is maintained below said conduits within said first conversion chamber; a gas removal conduit extending outwardly from said vessel at a level below said first partition but above the lower ends of said first plurality of conduits;

a second plurality of conduits extending tightly through said first partition so as to communicate on their inlet ends with said accumulation of contact material and extending downwardly through said first conversion chamber and tightly through said second partition and terminating a spaced distance below said second partition but above the lower end of said vessel so as to define a second conversion chamber within said vessel below said second partition with a compact reaction bed below the lower ends of said second plurality. of conduits and a plenum space above said bed but below said second partition; a plurality of spaced gas distributors connecting the upper end of "said second conversion chamber with the lower end of said first conversion chamber; a conduit for vapor flow connecting the portion of the conversion vessel above said first partition with the portion of said vessel below said second partition but above the lower ends of said second plurality of conduits; means for removing contact material from the lower section of said first conversion chamber; and means for removing contact material from the lower section of said second conversion chamber.

8. The apparatus of claim 7 further limitedto said means for removing contact material from said first and second chambers comprising a third plurality of conduits extending tightly through said second partition downwardly to a level in the lower section of said second conversion chamber and terminating on spaced apart outlets which arev sized so thatthe total horizontal area covered by said outlets is related to the horizontal area between said outlets in the same proportion as the desired contact material flow rate in the first conversion chamber is to the desired contact material flow rate through said second conversion chamber, and at least one contact material outlet conduit extending from said vessel at a level below the lower ends of said third plurality of conduits.

References Citedin the file of this patent UNITED STATES PATENTS Bergstrom Nov. 15, 1949 2,759,878 Berg Aug. 21,- 1956 

1. A PROCESS FOR THE CONVERSION OF HIGH BOILING FLUID HYDROCARBONS INTO LOWER BOILING GASEOUS PRODUCTS IN THE PRESENCE OF A MOVING MASS OF GRANULAR CONTACT MATERIAL, WHICH COMPRISES: MAINTAINING AN ACCUMULATION OF GRANULAR CONTACT MATERIAL WITHIN THE UPPER SECTION OF AN ENCLOSED HOUSING, CONTINUOUSLY SUPPLYING CONTACT MATERIAL TO SAID ACCUMULATION, SUPPLYING HYDROCARBON CHARGE, AT LEAST PARTIALLY IN THE LIQUID PHASE, TO SAID ACCUMULATION, REMOVING FROM SAID ACCUMULATION VAPOR FORMED FROM SAID LIQUID AND ANY GASEOUS MATERIAL SUPPLIED WITH SAID LIQUID, MAINTAINING A FIRST COMPACT REACTION BED OF CONTACT MATERIAL WITHIN SAID HOUSING BELOW SAID ACCUMULATION, MAINTAINING A SECOND COMPACT REACTION BED OF CONTACT MATERIAL A SPACED DISTANCE BELOW SAID FIRST REACTION BED AND WITHIN SAID HOUSING SO THAT A PLENUM SPACE IS DEFINED BETWEEN SAID BEDS, PASSING CONTACT MATERIAL AS AT LEAST ONE CONFINED STREAM FROM THE LOWER SECTION OF SAID ACCUMULATION ONTO THE UPPER SURFACE OF SAID FIRST REACTION BED, PASSING CONTACT MATERIAL FROM THE LOWER SECTION OF SAID ACCUMULATION ONTO THE UPPER SURFACE OF SAID SECOND REACTION BED, PASSING THE GASEOUS MATERIAL DISENGAGED FROM SAID ACCUMULATION INTO SAID PLENUM SPACE, PASSING GASEOUS HYDROCARBON MATERIAL FROM SAID PLENUM SPACE INTO THE LOWER END OF SAID FIRST REACTION BED 